Rapid exchange enteral stent delivery system

ABSTRACT

Methods of and devices for palliating gastrointestinal strictures using rapid exchange type enteral stent placement catheters. The catheter may include an inner member and an outer member, with the two members being slidable with respect to one another. In various device embodiments, a ramp for directing a guidewire out from within the catheter is provided using portions of the outer member or a shaped mandrel. The inner member may take a number of forms, including a tubular distal portion, a skived or integrally attached elongate midsection, and a proximal portion. A mandrel can be used in a portion proximal of the guidewire ramp, with the mandrel taking one of several disclosed forms.

REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 60/888,189, filed Feb. 5, 2007, the entire disclosure of which isincorporated herein by reference.

This application is related to U.S. patent application Ser. No.11/525,269, filed Sep. 22, 2006; which is a continuation of co-pendingU.S. application Ser. No. 11/094,401, filed Mar. 30, 2005; which is acontinuation of U.S. application Ser. No. 10/785,350, filed Feb. 24,2004, now U.S. Pat. No. 6,890,317; which is a continuation of U.S.application Ser. No. 10/454,269, filed Jun. 4, 2003, now U.S. Pat. No.6,723,071; which is a continuation of U.S. application Ser. No.09/808,626, filed Mar. 14, 2001, now U.S. Pat. No. 6,592,549; the entiredisclosures of which are all incorporated herein by reference.

FIELD

The present invention is related to the fields of medical devices andmedical procedures. More particularly, the present invention is relatedto devices and methods for treatment of enteral obstructions such as astent and a stent delivery system.

BACKGROUND

Endoscopic procedures for treating abnormal pathologies within thealimentary canal system and biliary tree (including the biliary,hepatic, and pancreatic ducts) are increasing in number. The endoscopeprovides access to the general area of a desired duct using directvisualization. However, the duct itself must be navigated using acatheter in conjunction with a guidewire under fluoroscopy. A widevariety of catheters are known for treatment of such targeted anatomicalregions. Examples of biliary catheters are disclosed in U.S. Pat. No.5,921,971 to Agro et al. and PCT International Publication No. 00/69498to De Toledo et al., the disclosures of which are hereby incorporated byreference.

Agro et al. disclose a catheter for use in biliary procedures, whereinthe catheter includes a shaft having a proximal end and a distal end. Aguidewire lumen extends through the shaft from a proximal guidewire portlocated proximal of the distal end of the shaft, to a distal guidewireport located at the distal end of the shaft. The shaft may also includea slot or channel extending from a proximal end of the shaft to theproximal guidewire port. Catheters incorporating such a guidewireopening and channel are often referred to as rapid exchange orsingle-operator-exchange type biliary catheters.

De Toledo et al. disclose a single operator drainage catheter deliverysystem including a guide member having a guidewire lumen extendingthrough a distal portion thereof, with a proximal guidewire port locateddistal of the proximal end. A placement catheter disposed over the guidemember has a catheter lumen extending through a distal portion thereof,with a proximal guidewire port located distal of the proximal end.Locating the proximal guidewire ports as such allows the delivery systemto be used by a single person with a shorter guidewire. A drainagecatheter (a.k.a. a plastic stent) is disposed about the guide memberdistal of the placement catheter. The drainage catheter delivery systempreferably includes a means for releasably connecting the placementcatheter to the drainage catheter, wherein the releasable connectingmeans disconnects the drainage catheter upon displacement of the guidemember. However, De Toledo et al. '498 does not disclose a rapidexchange biliary catheter system for the delivery of a metallicself-expanding stent, which requires a retractable sheath.

U.S. Pat. No. 5,484,444 to Braunschweiler et al., and U.S. Pat. No.5,709,703 to Lukic et al. disclose a stent delivery device which has anelongated sheath with a self-expandable stent placed in contractedcondition within the distal area of the sheath. An elongated core isarranged in the sheath for longitudinal motion relative to the sheath tofacilitate stent delivery. However, Braunschweiler et al. '444 and Lukicet al. '703 do not provide a rapid exchange feature as in De Toledo etal. '498.

U.S. Pat. No. 5,743,874 to Fischell et al. discloses a catheter capableof performing balloon angioplasty followed by delivery of aself-expanding stent. The catheter includes an outer sheath which may bepulled back to deploy the self-expanding stent. In one embodiment, thecatheter includes a guide wire entry port located just proximal of thestent to permit rapid exchange capability. To provide the guide wireentry port, Fischell et al. '874 provides a sloped plug disposed in theinner tube and an elongate side opening in the outer sheath. Theelongate side opening in the outer sheath is necessary to permitretraction of the outer sheath for stent deployment. By providing such along side opening, a major portion of the inner workings of the catheterare exposed to bodily fluids and interference from other devices, whichmay compromise performance of the stent delivery catheter. Thisundesirable feature, in addition to others not specifically mentionedherein, leaves a need for an improved rapid exchange stent deliverycatheter.

Gastrointestinal strictures in the duodenum and intestines are known tooccur for a variety of reasons, often due to impingement or compressioncaused by an adjacent tumor. A stent may be placed in an enteral regionin order to palliate a gastrointestinal structure, keeping a locationfrom being blocked and allowing a patient to have a more normal diet andlifestyle than would otherwise be possible. For example, a stent may beplaced by advancing a guidewire and ERCP catheter through an endoscopeworking channel into an enteral region for the purpose of contrastinfusion. The ERCP catheter can then be withdrawn, and a catheter loadedwith a self-expanding stent can be advanced over the guidewire to ornear an identified stricture. The stent is then released andself-expands to open the stricture. However, enteral stenting has beenperformed using over-the-wire devices only.

SUMMARY

The present invention, in an illustrative embodiment, includes a methodof palliating a gastrointestinal stricture using a rapid exchange typeof enteral stent placement catheter. The catheter may include an innermember and an outer member, with the two members being slidable withrespect to one another. The outer member includes a ramp that extendsdown into a guidewire channel in the inner member. The ramp may beslidable within the guidewire channel as well. The ramp is placed nearthe distal end of the catheter such that a guidewire need only traversea distal section of the inner member. Nearer the distal end of thecatheter, a self-expanding stent is placed between the inner member andthe outer member when the outer member is in a first position. Bycreating relative movement between the inner member and the outermember, the stent may be released by causing the outer member to nolonger cover the self-expanding stent. Once released, the stentself-expands to at least partially unblock the stricture.

In another embodiment, a rapid exchange catheter for deployment of aself-expanding stent includes an outer member having a distal tubularrestraining section as well as a guidewire port, and an inner memberhaving a distal portion adapted to carry a self-expanding stent withinthe restraining section. A mandrel is provided within the outer member,the mandrel coupled with the outer member to preserve axial alignment ofthe distal end of the mandrel with the guidewire port. The distal end ofthe mandrel is shaped to form a ramp for allowing a guidewire tosmoothly pass from within the outer tubular member out through theguidewire port to the outside of the catheter.

The present invention further includes devices adapted for use as rapidexchange type stent placement catheters. In a first illustrativeembodiment, a rapid exchange type catheter for use with a self-expandingstent includes an outer tubular member, an inner member, and a mandrel.In the illustrative embodiment, the inner member includes a distaltubular member coupled to the distal end of a proximal elongate member.For the illustrative embodiment, the outer tubular member includes aguidewire opening. The mandrel may be sized or shaped to fit next to theproximal elongate member within the outer tubular member, and terminatesnear the proximal end of the guidewire opening of the outer tubularmember. In several further embodiments, the proximal elongate membertakes the form of a push wire or other solid member that connects to thedistal tubular member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a rapid exchange stent delivery catheter systemin accordance with an illustrative embodiment of the present invention,shown in the delivery state;

FIG. 2 is a plan view of a distal portion of the rapid exchange stentdelivery catheter system illustrated in FIG. 1, shown in the deploymentstate;

FIG. 3 is a plan view of a distal portion of the outer tubular member ofthe rapid exchange catheter illustrated in FIG. 1;

FIG. 4 is a plan view of an inner tubular member of the rapid exchangecatheter illustrated in FIG. 1;

FIGS. 5A and 5B are cross-sectional views taken along lines 5A-5A and5B-5B, respectively, in FIG. 4;

FIG. 6 is a plan view of a self-expanding metallic stent suitable fordelivery by the rapid exchange catheter illustrated in FIG. 1;

FIG. 7A is an isometric view of a guidewire sleeve of the outer tubularmember illustrated in FIG. 3;

FIG. 7B is a longitudinal section view of a guidewire sleeve illustratedin FIG. 7A;

FIGS. 8A-8C are longitudinal sectional views of a guidewire entry portas a self-expanding stent is released for an embodiment corresponding toFIG. 1;

FIG. 9 is an isometric view of a guidewire entry ramp for anotherembodiment having a ramp-ended mandrel;

FIG. 10 is a plan view of a rapid exchange stent delivery catheter usinga ramp-ended mandrel;

FIGS. 11A-11C are longitudinal sectional views of a guidewire entry portas a self-expanding stent is released for an embodiment corresponding toFIG. 10;

FIGS. 12A-12F are cross sectional views taken along lines A-A, B-B, C-C,and D,E,F-D,E,F, respectively, in FIG. 10;

FIG. 13 is a longitudinal sectional view of a guidewire entry port anddistal end of a rapid exchange stent delivery catheter having a proximalpush wire;

FIGS. 14A-14B are longitudinal sectional views of another guidewireentry port and distal end of a catheter having a ramp-shaped mandrel anda proximal push wire;

FIG. 15 is a longitudinal sectional view of yet another guidewire entryport and distal end of a rapid exchange stent delivery catheter;

FIG. 16 is a longitudinal sectional view of still another guidewireentry port and distal end of a rapid exchange stent delivery catheter;

FIG. 17 is an exploded view of a mandrel/ramp member including a band toprovide a guidewire entry port;

FIG. 18 is an isometric view of an assembled catheter incorporating themandrel/ramp member and band of FIG. 17;

FIG. 19 is a longitudinal sectional view of a guidewire entry port anddistal end of a rapid exchange stent delivery catheter including anintermediate tubular member across the guidewire entry port;

FIGS. 20A-20B are a partial side cross view and an exploded view ofanother illustrative embodiment wherein a ramp is coupled to an innermandrel and extends out to the outer member;

FIGS. 21A-21E are cross-sectional views taken along lines 21A-21A,21B-21B, 21C-21C, 21D-21D, and 21E-21E, respectively of FIG. 20B; and

FIG. 22 illustrates a method of assembling the illustrative embodimentof FIGS. 20A-20B and 21A-21E.

DETAILED DESCRIPTION

The following detailed description should be read with reference to thedrawings. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention. Those skilled in the art will recognize that the dimensionsand materials discussed herein are merely exemplary and are not intendedto limit the scope of the present invention, which is, of course,defined by the appended claims.

As used herein, the term pushwire is not intended to indicate that acatheter is steerable. Instead, the pushwire is used to transmit apushing force to a distal part of a catheter. For several embodiments, apushwire is used to transmit a pushing force (typically in conjunctionwith a corresponding pulling force) that causes a self-expanding stentcarried by a first tubular member and constrained by a second tubularmember to be expelled from the second tubular member and deployed at adesired location.

Refer now to FIGS. 1 and 2, which illustrate plan views of a rapidexchange stent delivery catheter system 10 in accordance with anembodiment of the present invention. The rapid exchange stent deliverycatheter system 10 includes a rapid exchange catheter 100 which isadvanced over a guidewire 30 (shown in phantom) to deliver and deploy aself-expanding stent 20 in a bodily lumen.

The rapid exchange stent delivery catheter system 10 is suitable forbiliary and/or gastrointestinal applications. In biliary applications,the rapid exchange stent delivery catheter system 10 is sized to fitwithin an endoscope (not shown) and to navigate to the desired site inthe biliary tract. In vascular applications, the rapid exchange stentdelivery catheter system 10 is sized to fit within an introducer sheath(not shown) and/or a guide catheter (not shown) to navigate to thedesired vascular site. In enteral applications, the rapid exchange stentdelivery catheter system is sized to fit within an endoscope (notshown), to navigate to the desired enteral site, and to enable expansionof a self-expanding stent (such as a Wallstent® produced by BostonScientific Corporation) sufficiently large to palliate an enteralstricture and allow digestive processes to occur.

The rapid exchange stent delivery catheter 100 includes an inner tubularmember 120 slidably disposed in an outer tubular member 140. The outertubular member 140 includes a lumen (not visible) extending therethroughto slidably accommodate the inner tubular member 120. The inner tubularmember 120 includes a guidewire lumen 130 (shown in FIG. 5A) extendingthrough a distal portion thereof to accommodate the guidewire 30.

To provide rapid exchange capability for the rapid exchange stentdelivery catheter 100, the guidewire 30 exits through a guidewireopening 170 in the outer tubular member 140 as will be discussed ingreater detail with reference to FIGS. 3, 7A and 7B. The guidewire 30extends through a relatively short guidewire lumen and enters through adistal guidewire opening in the inner tubular member 120, as will bediscussed in greater detail with reference to FIGS. 4, 5A and 5B. Inpractice, the device 100 may be inserted over the guidewire 30 from thetip end first.

A proximal handle 122 is connected to a proximal portion 124 of theinner tubular member 120. Similarly, a distal handle 142 is connected toa proximal portion 144 of the outer tubular member 140. The distalhandle 142 may be longitudinally displaced relative to the proximalhandle 122 to selectively expose or cover the self-expanding stent 20,which is disposed about a distal portion of the inner tubular member120. In FIG. 1, the distal handle 142 has been longitudinally displacedin the distal direction relative to proximal handle 122 such that theouter tubular member 140 covers the self-expanding stent 20. In FIG. 2,the distal handle 142 has been longitudinally displaced in the proximaldirection relative to proximal handle 122 to retract the outer tubularmember 140 relative to the inner tubular member 120 to expose and deploythe self-expanding stent 20.

With additional reference to FIG. 3, the outer tubular member 140includes, from the proximal end to the distal end, a proximal portion144, a main outer portion (not visible) a guidewire sleeve 160 and adistal outer portion 146. The proximal end of the proximal outer portion144 is connected to the distal handle 142. The distal handle 142 may beinjection molded over the proximal outer portion 144. The distal end ofthe proximal outer portion 144 is connected to the proximal end of themain outer portion (not visible). The distal end of the main outerportion (not visible) is connected to the proximal end of the guidewiresleeve 160, and the distal end of the guidewire sleeve 160 is connectedto the proximal end of the distal outer portion 146. The variousportions of the outer tubular member 140 may be connected by adhesive,by thermal means or by any other suitable means known to those skilledin the art.

For biliary applications, the proximal outer portion 144 may be formedof PEBAX®, having a length of approximately 8.0 inches (20.3 cm), anoutside profile of approximately 0.120 inches (9 F) (0.30 cm), and aninside diameter of approximately 0.083 inches (0.21 cm). The guidewiresleeve 160 is discussed in greater detail with reference to FIGS. 7A and7B. The main outer portion (not visible) may be formed of PEBAX®/wirebraid/PTFE composite, having a length of approximately 55.0 inches (140cm), an outside profile of approximately 6 F (0.079 inches), and aninside diameter of approximately 0.057 inches (0.145 cm). The distalouter portion 146 may be formed of PEBAX®/wire braid/PTFE composite,having a length of approximately 10.6 inches (27 cm), an outside profileof approximately 8 F (0.105 inches), and an inside diameter ofapproximately 0.090 inches (0.229 cm).

For an enteral application, the proximal outer portion 144 may be formedof PEBAX®, having a length of approximately 8.0 inches (20.3 cm), anoutside profile of approximately 0.120 inches (9 F) (0.30 cm), and aninside diameter of approximately 0.083 inches (0.21 cm). The main outerportion (not visible) may be formed of PEBAX®/wire braid/PTFE composite,having a length of approximately 55.0 inches (140 cm), an outsideprofile range of approximately 6 F-8 F (0.079-0.105 inches), and aninside diameter of approximately 0.057 inches (0.145 cm). The distalouter portion 146 may be formed of PEBAX®/wire braid/PTFE composite,having a length of approximately 10.6 inches (27 cm), an outside profileof approximately 10 F (0.131 inches), and an inside diameter ofapproximately 0.113 inches (0.286 cm). Depending upon the size of thestricture to be palliated, longer or larger distal outer portions may beused as well.

A radiopaque marker band 42 may be disposed adjacent the distal end ofthe distal outer portion 146 to facilitate radiographic placement of thecatheter 100 and to radiographically indicate the position of the outertubular member 140 relative to the inner tubular member 120 to aid indeploying the self-expanding stent 20.

With additional reference to FIGS. 4, 5A and 5B, the inner tubularmember 120 includes a distal inner portion 126 connected to the distalend of the proximal inner portion 124. The proximal inner portion 124and the distal inner portion 126 are essentially the same, except theproximal inner portion 124 is reinforced with a stainless steelhypotube. The inner portions 124/126 may be formed of PEEK, having alength of approximately 88.6 inches (225 cm), an outside profile ofapproximately 0.052 inches (0.13 cm), and an inside diameter ofapproximately 0.037 inches (0.094 cm). A jacket formed of LDPE, having alength of approximately 5.9 inches (15 cm), an outside profile ofapproximately 0.080 inches (0.20 cm), and an inside diameter ofapproximately 0.055 inches (0.14 cm) may be disposed about the innermember 120 to consume the clearance between the inner member 120 and theouter member 140 proximal of the stent 20 to prevent kinking. Thevarious portions of the inner tubular member 120 may be connected byadhesive, by thermal means or by any other suitable means known to thoseskilled in the art.

A distal head 132 is connected to the distal end of the distal innerportion 126 to limit distal displacement of the outer tubular member140. A distal bond region 134 is disposed immediately proximal of thedistal head 132. A holding sleeve 136 and a stent cup 138 preventslippage of the stent 20. Radiopaque marker bands 44/48 are disposed onthe distal inner portion 126 and are separated by a distanceapproximately equal to the length of the stent 20. The distal outerportion 146 of the outer tubular member 140 contains the self-expandingstent 20 during delivery.

The distal inner portion 126 includes a proximal guidewire opening 128and a distal guidewire opening 129. A guidewire lumen 130 extendsbetween the proximal guidewire opening 128 and the distal guidewireopening 129 to accommodate the guidewire 30 therein. The proximalguidewire opening 128 has a length which is greater than the length ofthe guidewire opening 170 of the guidewire sleeve 160. The length of theproximal guidewire opening 128 is sufficient to allow longitudinaldisplacement of the outer tubular member 140 relative to the innertubular member 120 to permit full exposure and deployment of theself-expanding stent 20. The length of the proximal guidewire opening128 is preferably slightly longer than the length of the constrainedportion of the stent 20 to avoid wedging the guidewire 30 between theinner tubular member 120 and the outer tubular member 140 prior to fulldeployment of the stent 20.

The guidewire lumen 130 may be eccentrically positioned in the distalinner portion 126 as seen in FIGS. 5A and 5B. For example, the upperwall may have a thickness of approximately 0.003 inches and the lowerwall may have a thickness of approximately 0.011 inches. The upperthinner wall portion may be removed (skived) to define the proximalguidewire opening 128. By removing only the thin-walled portion of thedistal inner portion 126, the column strength of the inner tubularmember 120 is not significantly compromised.

A solid mandrel (not shown) may be inserted into the proximal lumen (notvisible) of the inner tubular member 120 proximal of the guidewireopening 128 for improved column strength. The solid mandrel may beformed of stainless steel having an outside diameter of approximately0.030 inches with a tapered end. A stainless steel hypotube (not shown)having an outside diameter of approximately 0.079 inches may be disposedabout the proximal inner portion 124 for added column strength anddurability. The proximal handle 122 may be injection molded over theproximal end of the hypotube and the proximal end of the proximal innerportion 124.

A distal radiopaque marker 44 is disposed on the distal inner portion126 to radiographically mark the distal end of the stent 20. A proximalradiopaque marker 48 is disposed on the distal inner portion 126 toradiographically mark the proximal end of the stent 20. A mid radiopaquemarker 46 is disposed on the distal inner portion 126 distal of theholding sleeve 136 to radiographically facilitate deployment of thestent 20.

With reference to FIG. 6, the stent 20 may comprise any self-expandingstent suitable for enteral, biliary or intravascular applications. Forexample, the self-expanding stent 20 may comprise a metallic stentcommercially available from Boston Scientific Corporation under thetrade name Wallstent®.

With reference to FIGS. 7A and 7B, the guidewire sleeve 160 includes aproximal portion 164, a distal portion 162 and a lumen 166 extendingtherethrough. The distal portion 162 is flared to fit over and beconnected to the distal outer portion 146. The proximal portion 164 issized to fit within and be connected to the main outer portion.

A guidewire opening 170 extends through the exterior wall of theguidewire sleeve 160. A ramp 172 extends from the exterior wall into thelumen 166. When assembled, the ramp 172 extends through the proximalguidewire opening 128 of the inner tubular member 120 and into theguidewire lumen 130. The ramp 172 is moveable within the proximalguidewire opening 128 to facilitate a smooth transition of the guidewire30 from the guidewire lumen 130 to exterior of the catheter 100,regardless of the position of the outer tubular member 140 relative tothe inner tubular member 120.

The guidewire sleeve 160 may have a length of approximately 1.0 inch, adistal outside diameter of approximately 0.122 inches, a proximaloutside diameter of approximately 0.087 inches, a distal inside diameterof approximately 0.107 inches, and a proximal inside diameter ofapproximately 0.070 inches. The ramp 172 may be an integral extension ofthe exterior wall of the guidewire sleeve 160 and may have a length ofapproximately 0.090 inches and a width of approximately 0.50 inches. Theramp 172 may extend into the lumen 166 at an angle of approximately 30degrees.

The guidewire sleeve 160 may be an integral part of the outer tubularmember 140 but is preferably a separately manufactured component. Forexample, the guidewire sleeve 160 may be formed of injection moldednylon or polypropylene. If the guidewire sleeve 160 is injection molded,manufacturing artifacts such as hole 168 may be filled or removeddepending on the particular application. By manufacturing the guidewiresleeve 160 separately, more manufacturing flexibility and efficiency areachieved. For example, the guidewire sleeve 160 may be made of amaterial that is not melt sensitive or that is readily bonded tofacilitate connection to other catheter components using adhesive orthermal means. In addition, the guidewire sleeve 160 may be inspectedprior entering the production floor to eliminate non-conforming partsand increase efficiency. Further, the dimensions may be controlledbetter to provide greater consistency at bond sites. These and otheradvantages not specifically mentioned herein may be obtained bymanufacturing the guidewire sleeve 160 as a separate component, but suchis not essential to the present invention.

FIGS. 8A-8C are longitudinal sectional views of a guidewire entry portas a self-expanding stent is released for an embodiment corresponding toFIG. 1. The illustrative guidewire entry port 200 is shown having aguidewire 202 exiting the catheter 204. The catheter has an outer member206, an inner member 208, and a mandrel 210. The mandrel 210 may bedisposed, as noted above, within the inner member 206 to provideimproved column strength over a proximal portion of the catheter.

FIG. 8A corresponds to a configuration wherein a stent is constrained bythe outer member 206. As the inner member is slide distally with respectto the outer member 206, the mandrel 210, which is within the innermember 206, slides distally as well, as shown in FIG. 8B. FIG. 8Cillustrates the configuration at the guidewire entry port 200 when thestent is fully deployed. As shown, the mandrel 210 must be sized to stopshort of the entry port 200 to avoid interfering with the guidewire 202.

A potential problem for the configuration of FIGS. 8A-8C is the distancebetween the distal end of the mandrel 210 and the guidewire entry port200. The mandrel 210 is included to provide added column strength, butdoes not span the guidewire entry port 200. The outer member 206 is cutat the guidewire entry port 200, weakening the outer member 206. Theinner member 208 is skived across the guidewire entry port 200, and is,therefore, also weakened. These three conditions make the region of theguidewire entry port 200 subject to crimping due to relative weakness ascompared to adjacent locations. It should also be noted that as thecatheter is advanced, the stent is constrained as shown in FIG. 8A. Thisis the period in which the pushability of the catheter is mostimportant, since once the stent is deployed, the catheter need not beadvanced further. Yet the configuration for advancement is the time inwhich the catheter is weakest in the region of the guidewire entry port200 because the mandrel 210 stops proximally thereof.

A further problem may occur when the stent is to be deployed. Inparticular, when relative pushing and pulling occurs between the innermember 208 and outer member 206, there is a potential for the catheterto deflect, causing inaccurate stent placement. For example, as theouter member 206 is withdrawn to deploy the stent (not shown), theskived inner member 208 can deflect at a location in the skived region(particularly to the side that is skived), causing the distal end of thecatheter to deflect. Likewise, if, at a stage of partial deployment, itis determined that stent placement is incorrect, a decision may be madeto seek to push the outer member distally to pull the stent back into arestrained position. Again, such a step can create lateral deflection.At locations where the guidewire is disposed within the catheter, it iseasier to retain a straight configuration, because the guidewireprovides at least some support to the catheter. However, this support isnot as easily provided proximate to and proximal of the guidewire port.

FIG. 9 is an isometric view of a guidewire entry ramp for anotherembodiment having a ramp-ended mandrel. The catheter 240 includes aguidewire entry port 242, outer member 246, inner member 248, and amandrel 250 having a slanted or ramp-shaped distal end. While the FIG.7A illustrates forming a ramp using the outer member, FIG. 9 insteaduses a specially shaped mandrel 250. This modification allows for asimpler treatment of the outer member 246. By having the mandrel 250form the ramp for causing a guidewire to exit the catheter, pushabilitymay be improved in the region of the guidewire entry port 242, since theguidewire provides support in and distal of the guidewire entry port242, and the mandrel extends to the guidewire entry port 242.

FIG. 10 is a plan and partial cut-away view of a rapid exchange stentdelivery catheter according to FIG. 9. The catheter 240 is shown havinga guidewire port 242 which allows a guidewire 244 to exit the catheter240. The inner member 248 is shown as carrying a stent 252 (shown bycutting away a portion of the outer member 246) and having a distal cap256. The inner member 248 may be crimped or skived across the guidewireport 242. As illustrated by the placement of the guidewire 244, theinner member 248 does include an opening allowing entry of the guidewire244 thereto and passage through a lumen in the inner member 248 to thedistal end of the catheter 240.

The catheter 240 also includes two proximal end handles, a first handle258 coupled to the outer member 246 and a second handle 260 coupled tothe inner member 248. The handles 258, 260 allow a physician to easilyslide the inner member 248 with respect to the outer member 246. Asshown and in contrast to several of the above-noted designs, the mandrel250 is attached to the first handle 258, such that it is coupled to theouter member 246 rather than the inner member 248.

FIGS. 11A-11C are longitudinal sectional views of a guidewire entry portas a self-expanding stent is released for an embodiment corresponding toFIG. 10. FIG. 11A shows the guidewire 244 exiting the guidewire port 242with the mandrel 250 in providing an exit ramp. As the stent ispartially deployed in FIG. 11B, and fully deployed in FIG. 11C, themandrel 250 does not move with respect to the guidewire port 242, sincethe port 242 and the mandrel 250 are coupled directly to the outermember 246. This means that, as illustrated in FIGS. 11A-11C, themandrel 250 does not move with respect to the outer member 246 and theguidewire port 242. Thus, the added pushability provided by the mandrel250 is made usable during insertion and advancement of the catheter 240,before deployment of the stent 252.

FIGS. 12A-12F are cross sectional views taken along lines A-A, B-B, C-C,and D,E,F-D,E,F, respectively, in FIG. 10. Note that FIGS. 12D-12F arealternatives to one another illustrating different proximalconfigurations for the mandrel 250 and the inner member 248. As shown inFIG. 12A, the outer member 246 and inner member 248 are generallycoaxial. The guidewire 244 passes through a lumen defined by the innermember 248.

FIG. 12B is closer to the guidewire port 242 (FIG. 10), and shows that aportion of the inner member 248 has been skived off or otherwise removedto allow the guidewire 244 to enter the lumen of the inner member 248.At the guidewire port 242 (FIG. 10), as shown in FIG. 12C, both theinner member 248 and the outer member 246 have a generally crescentshape allowing the guidewire 244 to enter the catheter. Severalalternative configurations proximal of the guidewire port 242 (FIG. 10)are shown in FIGS. 12D-12F.

FIG. 12D corresponds generally to that shown in FIG. 10, illustratingthat the inner member 248 resumes a tubular shape proximal of theguidewire port 242 (FIG. 10) and the mandrel 250 passes therethrough. Inorder to have the mandrel 250 coupled to the first handle 258 (FIG. 10),the inner member 248 may be skived or otherwise have a portion removednear the proximal end of the inner member 248. This allows the mandrel250 to pass outside the inner member 248 and couple to either the outermember 246 or the first handle 258 (FIG. 10). This coupling limitsrelative axial movement of the outer member 246 and the mandrel 250.

FIG. 12E corresponds to a first alternative configuration where theinner member 248 has a crescent shape (for example, by removing aportion of a hypotube) proximal of the guidewire port 242 (FIG. 10) tothe proximal end, at least, of the mandrel 250. Another alternative isshown in FIG. 12F, where the inner member 248 is shown as a push or corewire. The mandrel 250 may be shaped to secure the inner member 248 wirein an un-kinked or bent configuration, as shown. For the embodiment ofFIG. 12F, the wire portion of the inner member 248 may be attached byany of a number of methods (i.e., welding, brazing, or adhesive, forexample) to the more distal crescent-shaped and/or tubular portions ofthe inner member 248. Although the mandrel 250 is shown as beingsignificantly larger than the inner member 248 for purposes ofillustration, this need not be the case.

FIG. 13 is a longitudinal sectional view of a guidewire entry port anddistal end of a rapid exchange stent delivery catheter 280 having aproximal push wire. The guidewire entry port 282 allows a guidewire 284to exit the catheter. An inner member includes a distal tubular section286 and a proximal push member 288 which is illustrated in the form of awire. The outer member includes an outer distal member 290, from which aflap has been used to make a ramp 292. The outer distal member 290 issecured to an outer proximal member 294.

In one embodiment, the outer proximal member 294 is a smaller borehypotube, and the outer distal member 290 is a larger bore polymericmember. In another embodiment, the outer proximal member 294 takes theform of a dual lumen side-by-side elongate member. A mandrel 296 mayoptionally be included. The several integral parts of the catheter 280may be secured together by any of a number of methods, including thermaland adhesive processes.

FIGS. 14A-14B are longitudinal sectional views of another guidewireentry port and distal end of a catheter having a ramp-shaped mandrel anda proximal push wire. Referring to FIG. 14A, the catheter 300 includes aguidewire port 302 where a guidewire 304 exits the catheter 300. Aninner member includes a distal tubular member 306 on which a stent 308is disposed, and which ends in a distal head 310. The distal tubularmember 306 is attached on its outside, near its proximal end, to a pushwire 312 that extends toward the proximal end (not shown) of thecatheter 300.

A distal outer member 314 is illustrated as well, with the outer member314 having been skived or trimmed to remove a portion for creating theguidewire port 302, as shown at 316. The distal outer member 314 isattached to a proximal outer member 318. A mandrel 320 having aramp-shaped distal end is included, and may be secured in a manner whichcauses it to move axially in a one-to-one ratio with the outer members314, 318.

In one embodiment, a handle at the proximal end (not shown) of thecatheter 300 is attached to both the mandrel 320 and the proximal outermember 318. In another embodiment, the mandrel 320 may be secured to theproximal outer member 318 at some location along the length thereof. Forexample, if the proximal outer member 318 is provided as a hypotube, ametal mandrel 320 may be brazed or welded to the hypotube.

One known problem for some rapid exchange catheters having inner andouter members that are slidable with respect to one another isalignment. If the inner member is a tubular member along the length thatcrosses the guidewire port, then the opening in the inner member for theguidewire exit must align with the opening of the outer member for theguidewire exit port. Otherwise, the guidewire is subject to addedfriction or pinching at the guidewire exit port, making relativemovement between the guidewire and the catheter difficult. However, ifthe inner member is not a tubular member across the guidewire port,which is the case for several embodiments herein (including FIGS.14A-14B), the alignment problem is alleviated.

FIG. 14A illustrates the catheter 300 in a non-deployed configuration.To deploy the stent 308, the inner tubular member 306 is advanced by thecombination of a pushing force applied to the push wire 312 and apulling force applied to the proximal outer member 318. As the stent 308passes the distal end of the outer member 314, it self-expands tounblock or palliate a stricture in a body lumen, as shown in FIG. 14B.

FIG. 15 is a longitudinal sectional view of yet another guidewire entryport and distal end of a rapid exchange stent delivery catheter. Thecatheter 400 includes a guidewire port 402 allowing a guidewire 404 topass from within the catheter 400 to the exterior. A distal tubularmember 406 carries a stent 408 and is attached to a distal head 410. Apush wire 412 is attached to the distal tubular member 406.

A distal outer member 414 has a ramp formed therein at the guidewireport 402. The ramp may be formed by any number of methods. For example,the ramp can be formed by making a partial circumferential cut in thedistal outer member 414, making a longitudinal slit in the distal outermember extending proximally from the partial circumferential cut, usingone or more mandrels to hold the cut portions in a desired ramp shape,and applying heat to cause melting or at least re-flow of the distalouter member 414 material. Instead of the longitudinal slit, the distalouter member 414 may be held in a crimped configuration and heated toform the ramp.

In FIGS. 13, 14A and 14B, the pushwires 288, 312 attach to the outsideof the distal tubular members 286, 306. As shown in FIG. 15, thepushwire 412 attaches to the inside of the distal tubular member 406. Asillustrated by FIG. 15, this inner attachment allows the distal tubularmember 406 to be sized more closely to the size of the distal outermember 414. By extending the pushwire 412 well into the distal tubularmember 406, indeed, to the distal head 410, the pushwire 412 is used totransmit the pushing force, allowing the distal tubular member itself tobe a very thin-walled piece.

FIG. 16 is a longitudinal sectional view of still another guidewireentry port and distal end of a rapid exchange stent delivery catheter.The catheter 500 includes a guidewire port 502 allowing a guidewire 504to exit the catheter 500. A distal inner member 506 carries a stent 508and extends to a distal head 510. The distal inner member 506 is coupledto a pushwire 512, which spans the guidewire port 502 and couples to aproximal member 514 which is shown in the form of a round elongatemember that may be hollow, filled, or solid.

The outside of the catheter 500 includes three main parts, a distalouter member 516, a midshaft 518, and a proximal member 520. The rampfor the guidewire port 502 is defined by the midshaft 518, which may beshaped by any number of methods such as the cut, slit and re-flow orcrimp and melt methods discussed above with respect to FIG. 15. Thedistal outer member 516 may be attached during the steps of forming theramp, or may be placed later. The midshaft 518 is also attached to theproximal member 520 which, in several embodiments, is a hypotube.

It should be noted that for several embodiments herein, the cathetersmay be considered “convertible”. For example, the catheter 500 can beinitially placed over a first guidewire that exits the catheter at theguidewire port 502. If the first guidewire proves to be unsuitable forthe particular lesion or stricture being treated (for example, it may betoo flexible to pass a stricture, or may not be suitable for preciseadvancement), the guidewire may be withdrawn and a second guidewireadvanced through the proximal inner member 514 to the ramp.

The inner members are movable with respect to the outer member; the rampneed not completely or tightly seal (indeed, too tight of a seal mayimpede relative movement needed to deploy the stent 508) thereabout. Invascular applications, blood is a relatively sticky fluid, so it isuseful to provide tight seals to keep the blood from entering guidewirelumens and limiting guidewire movement. However, this problem is greatlyreduced in biliary applications so that tighter seals are not always anecessity (though the fluids tend to be more corrosive and can createother problems). Because the second guidewire will advance to the backside of the ramp, it will be directed by the ramp to the location wherethe inner member (i.e., push wire 512) passes the ramp, and may pass bythe ramp by passing adjacent the inner member (push wire 512). Thesecond guidewire can then be advanced to the distal end of the catheter500.

FIG. 17 is an exploded view of a ramp member including a band to providea guidewire entry port. The mandrel/ramp member 530 is formed having amandrel portion 532 coupled at its distal end of a ramp piece 534 havinga ramp 536. To help secure the ramp piece 534 to the outer member (notshown), a band 538 is included. As shown in FIG. 18, the ramp 536 andband 538 are secured about the outer member 540, which at leastpartially encloses the inner member 542. The band 538 may be secured tothe ramp 536 by any suitable manner, including the application ofadhesives, welding, and/or snap fit.

FIG. 19 is a longitudinal sectional view of a guidewire entry port anddistal end of a rapid exchange stent delivery catheter including anintermediate tubular member across the guidewire entry port. Thecatheter 600 includes a guidewire port 602 allowing a guidewire 604 toexit the catheter 600. A distal tubular member 606 carries a stent 608and ends in a distal head 610. The distal tubular member 606 is attachedto a push wire 612 that passes to the proximal side of the guidewireport 602.

The distal outer member 614 is cut to remove a portion at the guidewireport 602. The proximal end of the distal outer member 614 is attached toa proximal outer member 616 that may be a polymeric or reinforcedpolymeric tube, but is preferably a hypotube. For the illustrativeexample of FIG. 19, the proximal end of the distal outer member 614 hasbeen crimped or slit and compressed against the distal end of theproximal outer member 616 to achieve attachment thereto, as shown by thetaper at 622. This enables use of a lower profile proximal outer member616.

An intermediate tubular member 618 is also illustrated. The intermediatetubular member 618 is used to aid in making the ramp 620 that directsthe guidewire 604 out of the catheter 600. To make the ramp, a firstmandrel is passed through the intermediate tubular member 618, and theintermediate tubular member 618 is placed within the distal outer member614. A partial circumferential cut is made in the distal outer member614 to define the distal edge of the guidewire port 602. Proximally ofthe cut, the distal outer member 614 is then crimped down to theintermediate tubular member 618. Additional mandrels may be placed toretain the patency of the distal outer member 614 during the next step,which includes heating the distal outer member 614 in the region of theramp 620 to cause melting and/or reflow of the catheter 600 material.The intermediate tubular member 618 aids in providing pushability forthe whole catheter 600, as well as providing directional control overthe push wire 612 across the guidewire port 602.

FIGS. 20A and 20B provide an exploded and side section view of anotherillustrative embodiment wherein a ramp is coupled to an inner mandreland extends out to the outer member. The catheter 700 includes a mandrel702, inner member 704 and outer member 706. The distal end of themandrel 702 is connected to a ramp member 708 including guidewire ramp710. The inner member 704 includes a skived portion 712. As shown, theramp member 708 is secured to both the mandrel 702 and the outer member706. In one such embodiment, the mandrel 702 may have an unsecuredproximal end, and is provided for stiffness support. In anotherembodiment, the mandrel 702 may be secured near its proximal end to theouter member 706, or to an element secured to the outer member 706.

FIGS. 21A-21E are cross-sectional views taken along lines 21A-21A,21B-21B, 21C-21C, 21D-21D, and 21E-21E, respectively, of FIG. 20B. Asshown in FIG. 21A, the mandrel 702 is disposed within the inner member704 and outer member 706. Moving distally to FIG. 21B, the mandrel 702has been secured to the ramp member 708 near its distal end, at alocation corresponding to the skived portion 712 of the inner member.The ramp member 708 may be secured to the mandrel 702 by any suitablemethod, for example, using heat, welding, adhesives, and/or insertmolding, for example.

Going distally again to FIG. 21C, the ramp member 708 and the guidewireramp 710 can be seen. The ramp member 708 is secured to the outer member706 by any suitable method. The illustrative embodiment of FIG. 21Cshows the ramp member 708 secured to the outer member 706 using a lapjoint that is heat welded together, for example, with the use of acrescent shaped mandrel and a hot die, or by a laser method.Alternatively, an adhesive may also be used. Because the ramp member 708is secured to both the mandrel 702 (FIG. 21B) and the outer member 706,there is no variable “gap” from the distal end of the mandrel 702 to theramp 710 and/or the opening or skived portion 714 of the outer member706.

Now turning to FIG. 21D, it can be seen that just distal of the rampshown in FIG. 21C, the outer member 706 is disposed about the skivedportion 712 of the inner member 704. Preferably, the skived portion 712of the inner member 704 extends for at least the length of a stent to bedelivered such that the inner member 704 is slidable with respect to theramp member 710 along the skived portion 712. As shown in FIG. 21E,distal of the skived portion 712 (FIGS. 21C, 21D) the inner member 704again has a generally circular shape. If desired, the inner member 704may be a multi-piece member having at least the skived portioncomprising a hypotube member, with other portions being hypotubes,tubular polymeric pieces, or one or more polymeric pieces includingbraided support members. A stent 716 is shown disposed between the innermember 704 and outer member 706.

FIG. 22 illustrates a method of assembling the illustrative embodimentof FIGS. 20A-20B and 21A-21E. As shown, the inner and outer members arealigned such that the skived portion 712 of the inner member 704 alignsgenerally with a relatively short opening 714 in the outer member 706.Next, the proximal end of the mandrel 702 is inserted and advanced in aproximal direction through the opening 714 such that the proximal end ofthe mandrel 702 passes into the inner member 704. The mandrel 702 ismoved proximally until the ramp member 708 enters the opening 714 andthe ramp 710 engages the outer member 706.

Those skilled in the art will recognize that the present invention maybe manifested in a variety of forms other than the specific embodimentsdescribed and contemplated herein. Accordingly, departures in form anddetail may be made without departing from the scope and spirit of thepresent invention as described in the appended claims.

1. A rapid exchange type catheter adapted for placing a self-expandingstent, the catheter comprising: an outer member having a proximalportion, a distal portion, and a guidewire port therebetween, the distalportion adapted to cover a self-expanding stent, an inner member havinga proximal portion and a distal portion, the distal portion including aguidewire channel for passing a guidewire, the distal portion adapted toreceive a self-expanding stent thereon, wherein the inner member islongitudinally displaceable with respect to the outer member fordeploying a stent; and a mandrel member having a distal end and aproximal end, wherein the distal end has a ramp, the proximal end iscoupled to the proximal portion of the outer member so as to preventlongitudinal displacement of the mandrel with respect to the outermember when the inner member is longitudinally displaced with respect tothe outer member for deploying a stent.
 2. The catheter of claim 1,wherein the mandrel is disposed within the outer member such that theramp is located near the guidewire port of the outer member.
 3. Thecatheter of claim 1, wherein the inner member, outer member, and mandrelare shaped and sized such that the mandrel and the inner member extendwithin the outer member.
 4. The catheter of claim 3, wherein the mandrelfits within the inner member for a proximal portion of the length of theinner member.
 5. The catheter of claim 3, wherein the mandrel does notfit within the proximal portion of the inner member.
 6. The catheter ofclaim 3, wherein the mandrel and the proximal portion of the innermember lie within the outer member in a generally side-by-side fashion.7. The catheter of claim 1, wherein the outer member is movable withrespect to the inner member.
 8. The catheter of claim 1, wherein theouter member and the mandrel are coupled directly.
 9. The catheter ofclaim 1, wherein the outer member and the mandrel are coupled to by acommon element.
 10. The catheter of claim 1, further comprising a firstproximal apparatus and a second proximal apparatus, the first proximalapparatus attached to the proximal end of the outer member and theproximal end of the mandrel, the second proximal apparatus attached tothe proximal end of the inner member.